There are many ways you can help make Groovy a better piece of software - and we can use all the help we can get. Please dive in and help!

Try surfing the documentation - if something is confusing or not clear, let us know - or better still fix it for us. All of this website is maintained in a wiki, so please go right ahead and fix things if they are wrong or contribute new documentation.

Want to do some hacking on Groovy? Try surfing the issue tracker (see below) for open issues or features that need to be implemented, take ownership of an issue and try to fix it.

If you find a bug or a problem

If you can create a JUnit test case (either via Groovy or Java code) then your issue is more likely to be resolved quicker. Take a look at some of the existing unit tests cases, find one and modify it to reproduce your problem.

Then we can add your issue to Git and then we'll know when its really fixed and we can ensure that the problem stays fixed in future releases.

Contributing Code

The best workflow for this is to raise a new issue in the tracker (see below), fix the code in a branch on your forked project, and submit a pull request via the Github UI. Be sure to mention the JIRA issue id in the pull request and to add the pull request id to the JIRA ticket so that both are tied together. This workflow is described in more detail in a blog post here.

If you plan to contribute a "big" enhancement please discuss it on the developer mailing list first. Give everybody a few days for discussion before you start working. This assures that you do not waste time implementing a feature that could be rejected later on.

Instead of pull request we also accept patches. Please attach these to a JIRA issue

Improvements that need your help

Here's a list of some issues contributors could have a look at, to get started contributing to Groovy. You can also contribute to unassigned issues/enhancements without the "contrib" tag, just add the comment about your intentions in this issue and start working on it.

The following table is a summary of the fields where we would like to improve Groovy but do not find enough time to implement those features. For each of them, you will find a short description, an idea of the skills you need to implement them and the level of difficulty. Of course, getting into Groovy Core can be sometimes hard, so we should always work as a team and each subject below would be followed by a mentor.

Feature

Description

Skills

Difficulty

Mentor

Status

Grammar rewrite

The current Groovy grammar is written using ANTLR 2. For maintenance reasons, we would like to migrate the grammar to ANTLR 3 or ANTLR 4. Originally planned for Groovy 3, we will probably not be able to do that if no one helps. It is an important background task which covers the grammar of Groovy, the grammar of Java and a good knowledge of the Groovy AST (for backwards compatibility).

Since Groovy 2.0, we have two flavours of bytecode: the dynamic bytecode, corresponding to the main and legacy Groovy, and a "static" bytecode, triggered using the @CompileStatic annotation, which is closer to what Java produces. Both need specific bytecode optimizations.

ASM, JVM Bytecode

Hard

Cédric Champeau

In progress

Javascript backend

Groovy runs on the JVM, but we would also like to see a Javascript backend. Of course, a prototype would have limited capabilities compared to what the JVM one offers, mostly because the Groovy language is not only a language but also a rich API relying internally on JDK APIs.

It is also important to take a look at what APIs are being written in JDK 8 because most of the APIs written for the new lambdas are specifically lazy.

Algorithmics

Medium

Paul King

Prototype

New MOP

The new MOP (Meta Object Protocol) is a key feature of Groovy 3. The objective is to rewrite the MOP totally, in order to provide a more consistent, powerful and performant MOP. See http://groovy.codehaus.org/MOP+2.0+ideas

Language theory

Medium

Jochen Theodorou

In progress

Bugfixes

As the language is widely used, we have a lot of bug reports. Unfortunately, the team is too small to tackle them all. If you find a bug that you think you can work on, do not hesitate to help!

Easy to hard

any member of Groovy core

In progress

Modularization

Groovy 2 came with the concept of modularization and is now splitted into modules. Each module is a logical group of features (for example, XML, JSON, Swing, ...). While Groovy core was reduced by half, there's still plenty of room for improvement and further modularization.

Architecture

Easy

Paul King

In progress

Documentation

On every project, documentation is never enough, nor up-to-date. Groovy falls into that trap too. A very good way to get into Groovy is to start documentation, fix documentation or improve javadocs. There are also side projects like a new website, a new Groovy Web Console which require some time but were never started.

Easy

Guillaume Laforge

In progress

Specification

Help joining the specification effort. The Groovy language has evolved a lot and there's no complete specification available yet.

Medium

Guillaume Laforge

Standby

Security

Help us improving java.security support in Groovy. We have, for example, unit tests failing periodically because of security tests (Security Manager related). No one in the team is an expert in that domain so any help would be very appreciated!

Java security

Medium

Cédric Champeau

Standby

Groovy for Android

A lot of us would like to see Groovy run on Android. There are some technical challenges but the good news is that some hackers (Marcin Erdmann and Erik Pragt) managed to do it for Groovy 1.7. It's not production ready yet, and we would like to have, at some point, support in the Groovy distribution itself (aka, no patch required). Running Groovy is one thing, doing something with it is another, so a side project for this is definitely to make Groovy a language of choice to build Android applications. We think some projects like Griffon, for example, have a strong interest in that, by making the design of UIs much easier.

The Groovy Console is a very nice tool. However, there are several things that can be improved: syntax highlighting, especially for large scripts, which is too slow; the AST Browser which can be improved in several ways (displaying node metadata, more focused bytecode view, ...)